Artist James Turrell has been building a massive work of art in the Arizona desert since the 1970s, but few have ever seen it. The artist, who specializes in perception-bending optical illusions he calls skyspaces, is turning Roden Crater, an extinct volcano crater more than a mile and a half wide, into a naked-eye observatory. And for the first time, people will be able to see it.

The piece, still under construction, has never been open to the public. A select few–like high-level curators and a New York Times reporter have secured invites. However, this May, the artist will open it up to a limited number of visitors. For $6,500 each, 20 visitors a day will be allowed into the 400,000-year-old extinct volcano over a four day period in May.

If it’s anything as mind-blowing as his typicalinstallations, we’d say it’s probably worth the price tag.